Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a process cartridge and an electrophotographic apparatus each including an electrophotographic photosensitive member, and a method for producing an electrophotographic photosensitive member.
Description of the Related Art
An electrophotographic photosensitive member used in an electrophotographic apparatus includes an undercoat layer containing a metal oxide particle and provided between a support and a photosensitive layer. The metal oxide particle is surface-treated with a silane coupling agent for suppressing black-dot image defects due to charge injection into the photosensitive layer side from the support.
Japanese Patent Laid-Open No. 2004-191868 describes that an undercoat layer of an electrophotographic photosensitive member contains a urethane resin and a metal oxide particle surface-treated with a silane coupling agent having an amino group.
Also, a urethane resin which is a curable resin is used as a binder resin (resin) in the undercoat layer. When a curable resin is used as a binder resin of an undercoat layer, from the viewpoint of productivity of the electrophotographic photosensitive member, it is required that curing at a low temperature (production of a curable resin at a low temperature) can be performed. Therefore, Japanese Patent Laid-Open No. 2004-198734 describes that an undercoat layer contains a curable resin produced by reaction of a polyvinylbutyral resin with a compound having an isocyanate group blocked with a diethyl malonate structure.
A silane coupling agent has, in a molecule thereof, both a hydrolyzable group which reacts with a metal oxide particle and modifies the surfaces thereof and an organic functional group which has an interaction with a binder resin. Since reactivity with the binder resin varies with the type of the organic functional group, it is required to select the organic functional group suitable for the binder resin used in the undercoat layer. When reactivity with the binder resin varies with the type of the organic functional group, black dots may be easily produced by aggregation of surface-treated metal oxide particles.
As a result of investigation of an undercoat layer using a curable resin (urethane resin) produced by reaction of polyol with a compound represented by formula (2) below, the inventors found the following problem. That is, when the urethane resin and metal oxide particle surface-treated with a silane coupling agent having an amino group or a mercapto group are used in the undercoat layer, a change in light-area potential may be easily increased in a high-temperature-high-humidity environment.

In the formula (2), X represents a single bond or an oxygen atom, and R1 and R2 each independently represent an alkyl group having 1 to 4 carbon atoms. When in the formula (2), X is an oxygen atom and R1 and R2 are each an ethyl group, the formula has a diethyl malonate structure.
An object of the present invention is to provide an electrophotographic photosensitive member in which both a change in light-area potential in a high-temperature high-humidity environment and black dots are suppressed at a high level. Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus each including the electrophotographic photosensitive member. A further object of the present invention is to provide a method for producing the electrophotographic photosensitive member.